python - pytest:在测试用例不可见的 fixture 中分配属性

Question

为什么我无法在 pytest fixture 中设置 self.param 值？

class TestClass:
    @pytest.fixture(scope='class', autouse=True)
    def setup_class(self, test_env):
        self.param = 2

    def teardown_method(self):
        remove_setting(self.param)
    
    def test_one(self):
        assert self.param == 2

    def test_two(self):
        assert len("hello") == 5

这导致

scratch.py::TestClass::test_one FAILED                                 

    def test_one(self):
>       assert self.param == 2
E       AttributeError: 'TestClass' object has no attribute 'param'

    def teardown_method(self):
>       remove_setting(self.param)
E       AttributeError: 'TestClass' object has no attribute 'param'

我想在设置期间设置此属性，因为我最终将使用该参数执行方法级拆卸(不是类级拆卸，所以我没有使用产量)。在这个例子中，我的测试看不到 self.param 值，我的拆卸函数也看不到。将 self.param = 2 移动到我所有的测试中很麻烦。有什么更好的方法来做到这一点？

Answer 1

如 docs说:

Something to be aware of when grouping tests inside classes is that each test has a unique instance of the class. Having each test share the same class instance would be very detrimental to test isolation and would promote poor test practices.

我建议使用这样的类范围 fixture :

import pytest

@pytest.fixture(scope='module')
def test_env():
    pass

@pytest.fixture(scope='class')
def param(test_env):
    return 2


class TestClass:
    def test_one(self, param):  # All tests methods share the same param
        assert param == 2

    def test_two(self, param):
        assert param == 3